The
air-surface discharge sparkplug with nickel sheathed copper core and 4
ground electrodes arranged in pairs in the form of an X provide maximum
ignition reliability in all operating situations.

The multifunction principle for optimal ignition reliability: various
principles of operation are available for the formation of the sparking
path  air discharge, surface discharge and combined air-surface
discharge. At the same time, the 4 ground electrodes are offset in height
in pairs. On the left the path to one of the two lower electrodes can
be seen, (surface discharge), on the right the two possibilities on one
of the upper electrodes (air discharge and air-surface discharge). In
this way there are six different paths for the ignition sparks.